World's First Combination of Acid & Steam Provides a New Dimension to Heavy Oil Enhanced Recovery Process (SPE 154515)

The Issaran field located200 km east of Cairo-Egypt, is a heavy oil reservoir.The oil is of 8-12 degree API with viscosity of 4000 cps at standard conditions. Productivity of the wells has sharply declined due to increase in water cut and increase in the formation skin value. The problem is attributed to the heterogeneity of the reservoir together with presence of fractures which is causing poor sweep efficiency plus the accumulation of hydrocarbon deposits. The major challenge to remedy this situation was; Not only the creation of new extended flow channels, accurate placement of the treatment, diversion within the reservoir, and to provide sustain production increase but also the flow and the production of oil through the newly formed wormholes. A new innovative approach using a combination of acid based treating fluids and steam were used. Acid in combination with unique chemical diverting agent plus selective placement mechanism succeeded to open new production horizons and stimulate the existing one. The Addition of Steam has succeeded in reducing the viscosity and increasing the mobility of oil, and also in providing pressure support to the reservoir achieving further increase in the benefits of the acid stimulation. The results of the treatments carried out so far have provided a new dimension in the enhanced recovery process of the heavy oil. This paper explains the design, execution, evaluation and the recommended way forward of this world first acid & steam production enhancement initiative for the reservoir enhanced recovery process.